Photocleavable and tunable thermoresponsive amphiphilic random copolymer: Self‐assembly into micelles, dye encapsulation, and triggered release

Abstract

A double‐responsive amphiphilic random copolymer (P(OEtOxA)‐ran‐PNBA) composed of thermoresponsive poly(oligo(2‐ethyl‐2‐oxazoline)acrylate) (P(OEtOxA)) segments and photocleavable poly(2‐nitrobenzyl acrylate) (PNBA) segments is synthesized via combination of cationic ring‐opening polymerization (CROP) and reversible addition‐fragmentation chain transfer (RAFT) polymerization techniques. The P(OEtOxA)‐ran‐PNBA copolymer exhibits lower critical solution (LCST)‐type soluble‐to‐turbid phase transition in water with tunable cloud point (Tcp) with respect to chain length of P(OEtOxA) segment present. The photocleavage of PNBA segments by UV irradiation transforms amphiphilic P(OEtOxA)‐ran‐PNBA to fully hydrophilic P(OEtOxA)‐ran‐poly(acrylic acid) resulting in the appreciable increase of Tcp of copolymer in aqueous solution. Owing to the amphiphilic nature, the P(OEtOxA)‐ran‐PNBA copolymer molecules self‐assemble into well‐dispersed spherical micelles in water. There is a disruption of the copolymer micelles with UV light irradiation as well as shrinkage of micellar size with increasing temperature above the LCST of copolymer in solution. Finally, the encapsulation of hydrophobic guest molecule (nile red) into P(OEtOxA)‐ran‐PNBA copolymer micelles and thermo‐ and photo‐triggered release of nile red are demonstrated. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1714–1729

Light-sensitive dextran-covered PNBA nanoparticles as triggered drug delivery systems: Formulation, characteristics and cytotoxicity

“…[31] Such bonds were already assessed to light-induce the disassembly of block copolymer micelles. [32][33][34][35][36] Very recently, some of us have reported the first controlled polymerization of o-nitrobenzyl acrylate (NBA), [37] then the synthesis of amphiphilic grafted photosensitive glycopolymers called Dex-g-PNBA, composed on dextran (Dex) as hydrophilic backbone and poly(o-nitrobenzyl acrylate) (PNBA) as photo-responsive grafts. [38] To the best of our knowledge, the formulation of nano-objects from polysaccharide/PNBA copolymers has never been reported.…”

Playing construction with the monomer toy box for the synthesis of multi‐stimuli responsive copolymers by reversible deactivation radical polymerization protocols

“…On the other hand, when a light‐sensitive moiety is located in the hydrophobic micellar core, the nanoaggregate can be photo‐stimulated to disassemble or modify its LCST. This is the case, for example, of photoacid generators, such as o ‐nitro benzylacrylate, 8,146,164 or N‐hydroxyphathalimide methacrylate, 165 which are photocleaved to yield hydrophilic and pH‐sensitive free acrylate groups. Coumarin moieties are incorporated in the design of functional polymers that can be used in electro‐optical studies, photoreversible systems, chiral stationary phases for HPLC, fluorescent tags and fluoroprobes 166 .…”

Dual Thermo- and Photo-Responsive Micelles Based on Azobenzene-Containing Random Copolymer

“…In Figure 9a, the Nile red-loaded NR-S3 solution not only still had a stron sorption band at about 360 nm, but also exhibited a characteristic absorption band of Ni at 588 nm, compared with S3micellar solution; in Figure 9b, a new characteristic fluores emission peak of S3 solution at about 645 nm was observed after being loaded with Ni According to the all above measurements, Nile red was successfully loaded. Nile red is a special dye molecule, which does not exhibit any fluorescence whe soluble in water, but the fluorescence intensity remarkably increased in the hydrop environment, for example, inside a hydrophobic micellar core [29]. In this case, the to-induced Nile red release of S3 micellar solution was investigated first.…”